DOSBox uses Ctrl-F11 and Ctrl-F12 to adjust emulated CPU speed.
Reload the page to reset CPU speed.
MORSE CODE TUTOR is largely unaffected by the CPU speed. You can decrease the CPU speed to introduced a pause after the 'fail buzzer' (before Morse plays again). Mash Ctrl-F11 a few times to do this.
FLASHING LIGHTS PRACTICE PROGRAM might run a little fast at the default DOSBox CPU speed but is usable. From a rough stopwatch test, it's 2% to 15% fast depending on whether it's using the CODEX or PARIS standard.
MORSE CODE TRAINING PROGRAM (aka "CW") plays Morse code inhumanly fast. Four separate methods to fix it:
Mash Ctrl-F11 maybe 12 times or so; OR
Adjusted timing within the program itself to work with Dosbox's
default CPU speed: Utilities > Timing > 32766 (which is the
maximum slowdown value, which is not quite enough but within 5% of what
it's meant to be); OR
Play CW v3.12 here with the original color palette, where the timing value is pre-adjusted; OR
Play the newer Super Morse from the same author, which does not have CPU-dependent audio speed.
Files from all three applications and from the menu system are all mixed together in the root directory.
CW has all its original files (matching v3.12), except the configuration (CW.CFG) is altered; and the user manual is missing (CW.DOC).